有大佬帮帮忙吗？

#include<bits/stdc++.h>
using namespace std;

int main(){
	char a1[2005], b1[2005];
	int a[2005], b[2005], c[2005];
	int lena, lenb, lenc, x;
	memset(a, 0, sizeof(a));	 
	memset(b, 0, sizeof(b));	 
	memset(c, 0, sizeof(c));
	gets(a1);gets(b1);
	lena = strlen(a1);lenb = strlen(b1);	 
	for(int i = 0; i <= lena-1; i++)
		a[lena-i] = a1[i] - 48;
	for(int i = 0; i <= lenb-1; i++)
		b[lenb-i] = b1[i] - 48;
	for(int i = 1; i <= lena; i++){
		x = 0;
		for(int j = 1; j <= lenb; j++){
			c[i+j-1]=a[i]*b[j]+x+c[i+j-1];//
			x=c[i+j-1]/10;
			c[i+j-1]%=10;
		}
		c[i+lenb]=x;
	}
	lenc = lena + lenb;
	while(c[lenc]==0&&lenc>1)
		lenc--;
	for(int i = lenc; i >= 1; i--)
		cout << c[i];
	cout << endl;
	return 0;
}

CE评测

https://www.luogu.com.cn/record/78830351